Coupling device for an appliance for domestic use

ABSTRACT

The invention is directed to a coupling device ( 1 ) for an appliance for domestic use, in particular a handheld blender, for connecting a drive part ( 7 ) to a tool shank ( 6 ), with a locking device ( 2 ) having locking elements ( 3 ) being arranged on a coupling section of the drive part ( 7 ), said locking elements being in engagement with depressions ( 10 ) formed on the inner circumference of the tool shank ( 6 ) in the locked state. The invention is characterized in that the locking device ( 2 ) is constructed as an annular spring element and that in the area of the locking element ( 3 ) provision is made for an actuating device ( 4 ) causing, when actuated, the spring element to be deformed elastically such that the locking element ( 3 ) moves inwardly, hence becoming disengaged from the detent element ( 10 ).

[0001] This invention relates to a coupling device for a kitchen machinein accordance with the prior-art portion of patent claim 1.

[0002] Coupling devices of this type for kitchen machines are known fromthe art. For example, FR 1467108 describes a device in which a socketarranged on a tool shank hooks elastically into the lower region of thedrive part. For this to happen the drive part has at its lower end alatch which, under the action of a helical spring, engages radially in agroove provided on the outer circumference of the socket. In thisarrangement the latch can be released by an actuating button which inthe latched position projects sideways out of the drive part.

[0003] From FR 1467108 there is also known an ejecting device which isintegrated in the drive part. According to this prior art, a helicalspring is biased when the tool shank is pushed in and used as an ejectorwhen released.

[0004] Furthermore, from EP 0692215 A1 there is known a handheld blenderwith a drive part and an interchangeable tool shank in which a toolshaft is rotatably mounted. To fasten the tool shank to the drive partan expansion clamp of the drive part engages in a mounting groove of thetool shank. To release the tool shank the expansion clamp, which isconstructed as a metal spring, is pushed by means of a pushbutton, whichis constructed as a separate component, in the direction of an oppositelying pushbutton.

[0005] It is an object of the present invention to provide a simple andlow-cost solution for connecting a tool shank to the drive part of anappliance for domestic use, particularly a handheld blender or immersionblender.

[0006] This object is accomplished by a coupling device with thefeatures of patent claim 1. A particularly simple coupling deviceaffording low-cost manufacture is provided by the construction of theinvention. The device of the present invention may find application notonly on handheld blenders such as immersion blenders but also onstand-alone kitchen machines or other electrical appliances for domesticuse. The coupling section of the drive part may be constructed, forexample, essentially as a cylindrical end portion having arranged in itsinterior the locking device. The upper part of the tool shank islikewise of an essentially cylindrical configuration at its innercircumference enabling it to slide over the coupling section of thedrive part quasi like a sleeve to be centered and axially fixed in placeon the cylindrical end portion. Furthermore, rotatably mounted in thetool shank is a tool shaft whose one end is adapted to be coupled withthe drive shaft of the drive part and whose other end projects into theblending space of a bell-shaped shield and is securely connected to aprocessing blade, such as was initially referred to in the prior art.

[0007] It will be understood, of course, that other annularconfigurations of the spring element, e.g., circular, prismatic,elliptical or other forms of ring, are also possible. With theseconfigurations the upper part of the tool shank, which is constructedessentially as a sleeve, is shaped to conform to the shape of thecoupling section of the drive part in order to be able to plug theseparts together. The detent element, which here is constructed preferablyas a depression provided on the inner circumference of the tool shank,may be constructed as a circumferential groove, for example, or as asingle elongated slot. In the event of the locking device beingconstructed as an ellipse, the points furthest apart from each other lieon the long diameter of the ellipse. If the spring element is shaped asa rhombus, the points furthest apart from each other lie on the longdiagonal.

[0008] The locking element may be formed by a projecting lug or a beador a depression, for example, which is integrally connected as aone-piece construction with the spring element and then engages in acorresponding depression or lug or other projection on the tool shank.The actuating device involved may be a bead which is formed on thespring element and has the function of a pushbutton. A multiple functionresults from the fact that both the actuating device and the lockingelement are integrally connected as one piece with the spring element,thereby reducing the number of additional components and having theactuating and locking function performed by a single component.

[0009] Through the superimposed arrangement of the actuating device andthe locking element the locking element is displaced radially inwardlywhen the spring element on the actuating device is pressed, as theresult of which it slides out of the detent element, thus releasing thetool shank for removal. According to the invention the actuating elementmay simultaneously form the locking element as well. According to theinvention the spring element is deformed by the actuating element beingpressed on the one side while the spring element takes support upon thehousing of the drive part on the other side.

[0010] An advantageous embodiment of the coupling device of the presentinvention is described by the features of patent claim 2. By virtue ofthe diametric arrangement of the locking and actuating elements it ispossible to press together the spring element in simple manner and withlittle force using the thumb and index finger of one hand, as the resultof which the locking elements move likewise in inward direction. Whenreleased, the spring element and the locking elements return to theirinitial position.

[0011] According to the features of patent claim 3 the openings for theactuating elements may be elongated or oval slots or, alternatively,openings shaped in a rectangular, circular or some other configuration.In the locked state the actuating elements project out through theseopenings and are therefore freely accessible from the outside foractuation. When actuated by hand the actuating elements partly disappearin the openings of the outer wall of the coupling section of the outerpart, as the result of which the locking elements also move inwardly andslide out of their detent elements, as the result of which the toolshank is in turn released and allowed to slide downward from thecoupling section and drive part.

[0012] Through the features of patent claim 4 it is possible for thespring element to be actuated particularly effectively and easily fromthe outside because the spring element is essentially symmetric inconstruction and pressed together uniformly from both sides when forceis applied.

[0013] According to the features of patent claim 5 the superimposedarrangement of the locking element and the actuating device results inthe path traveled on the actuating device being equal to the pathtraveled on the locking element, i.e., a direct transmission of travelresults with minimum actuating forces and displacement travels, leadingultimately to a simple and direct unlocking operation of the couplingdevice.

[0014] A particularly advantageous further aspect of the presentinvention is provided by the features of patent claim 6. Suitablematerials to be considered include, for example, elastic polypropylene,polyethylene or polyamide. These materials can be used forinjection-molded parts in a simple and low-cost manner. The inherentelasticity of these plastics guarantees that the spring element recoversits original form after being accordingly deformed as required.Furthermore, a multiplicity of functions can be performed by a singlecomponent through its construction as a one-piece plastic part.

[0015] An advantageous embodiment with the features of patent claim 7displays in particular the multiple function of the ejector constructedin one piece with the spring element. Components can be saved as theresult and the costs reduced accordingly. Furthermore, the functions ofthe ejector and the locking elements are skillfully interconnectedbecause the ejector is arranged at an angle of 90 degrees to the lockingelements in the case of a spring element of cylindrical configuration,on the short diameter in the case of a spring element of ellipticalconfiguration, and on the short diagonal in the case of a spring elementof rhombic configuration. When the locking device is accordinglyactuated by means of the actuating elements the spring element isdeformed for the releasing operation, thus enlarging the regions of thespring ring around the ejectors or the lengths of the short diagonals orshort diameters whilst compressing the actuating region of the springelement. The ejectors are thereby pressed against the obliquelyextending inner circumference of the tool shank, as the result of whichthe locking elements are unlocked and the tool shank simultaneouslydecoupled from the drive part, pushed away and thereby ejected axiallyin the longitudinal direction of the drive part.

[0016] A further advantageous multiple function is described by thefeatures of patent claim 8 in which the ejectors have ramp surfaceswhich, when actuated radially, effect an axial ejecting movement in thelongitudinal direction of the drive part. A flat ramp pitch is selectedso that the actuating forces are not too high for the operator but thetravel is still sufficient for the tool shank to be visibly disengagedfrom the drive part.

[0017] Finally, a further advantageous embodiment of the presentcoupling device is provided by the features of patent claim 9. Suitableguide devices, which may be formed, for example, by grooves provided onthe spring element and guide ribs on the drive part, are used to preventthe spring element from skewing, for example, thus ensuring a reliablefunction.

[0018] It is also particularly advantageous for the locking device ofthe present invention to exhibit the features of patent claim 10. Acaptivating device of this type may be provided, for example, by havingeither the ejectors or the locking elements—preferably the ejectors inthe embodiment—always engaged with the passages formed on the drivepart. Fixing the spring element in the drive part in this mannerfacilitates the assembly operation significantly because, onceinstalled, the spring element is fixed in its position. Slipping out ofthe predefined position and jamming with other components is therebyprevented. The ejectors penetrate the drive part and project out of itfar enough in radial direction as to latchingly engage in depressionsformed on the tool shank in order to act as detent elements when thetool shank is inserted.

[0019] A further advantageous embodiment of the present invention isprovided by the features of patent claim 11. It is thereby possible forthe locking elements to snap in place during the coupling operation,without the actuating devices being in the way. This is achieved byspatial separation of the locking elements relative to the actuatingdevices. When mounting the tool shank it is thus possible for thelocking elements to be pressed, without actuating the actuating device,back into the corresponding opening in the outer wall of the couplingsection until they are aligned with the depressions on the innercircumference of the tool shank. At this moment the locking elementssnap back on account of the spring action of the vertical connectingbar. The coupling connection is now engaged and locked. Unlocking is nowonly possible by actuating the actuating devices.

[0020] To improve the snap-action effect of the locking elements theyare constructed in accordance with patent claim 12. On the one hand thelocking elements thus act as a barb, on the other hand the centeringsurfaces on the tool shank cooperate with the sliding surfaces on thespring element, resulting in the spring element invariably urging thetool shank into the drive part without play, as the result of which thewalls are biased against the abutment surfaces because the springelement in the drive part always maintains a small bias.

[0021] According to the features of patent claim 13 the tool shankslides on the wedge-shaped ejector as on a ramp during the decouplingoperation. The additional spring action through the second connectingbars helps to control the ejection pressure. It also prevents skewing.

[0022] Further aspects and advantages of the present invention will beexplained by the following description of embodiments with reference tothe accompanying drawings. In the drawings,

[0023]FIG. 1 is a schematic representation showing in a partiallongitudinal sectional view an invention embodiment of a coupling devicefor an immersion blender;

[0024]FIG. 2 is a sectional view of the invention embodiment of FIG. 1turned through 90 degrees, but without motor, drive spindle, couplingsleeve and drive shaft;

[0025]FIG. 3 is a perspective view of the invention spring element ofthe coupling device of FIG. 1;

[0026]FIG. 4 and FIG. 4a are schematic representations of the functionof the invention embodiment of FIG. 1 in locked condition; and

[0027]FIG. 5 and FIG. 5a are schematic representations of the functionof the invention embodiment of FIG. 1 in unlocked condition.

[0028]FIGS. 1 and 2 show a schematic sectional view of an advantageousembodiment of the coupling device 1 of the invention. They show the toolshank 6 with its upper portion which embraces the lower frusto-conicalcoupling section 24 of the drive part 7 quasi like a sleeve. In thepresent embodiment the drive part 7 and the tool shank 6 aremanufactured mainly of plastic. As shown in FIG. 1 the tool shank 6 hasat its upper inner circumference locking recesses or detent elements 10which are constructed as elongated grooves for accommodating lockingelements 3. Fastened in a bore 15 of the drive part 7 is a bearingsleeve 16 having a bore 20 in which a further bearing sleeve 22 isfastened, which again has a bore 23 in which a plain bearing 25 isinserted, in which is rotatably mounted the drive spindle 26 of theelectric motor 27 non-rotatably mounted in the drive part 7. The freeend of the drive spindle 26 is non-rotatably fastened to a couplingsleeve 28 which has an accommodating bore 29 in which the drive shaft30, which is non-rotatably and releasably mounted in the tool shank 6,is non-rotatably and releasably coupled. Fastened to the other end, notshown in the drawings, of the tool shaft is a blade or processing tool(not shown) for processing food, which is surrounded by a shield,preferably a bell, of the type known from FR-B-1467108, for example.

[0029] The drive shaft 30 has driving elements, not shown in thedrawings, which engage in corresponding driving elements (not shown) inthe accommodating bore 29 in a non-rotatable but releasablerelationship. According to FIG. 1 the bearing sleeve 16 has an annularcollar 17 with 90° offset, which takes support upon and centers itselfon the bore 15 of the housing 18 at the drive end.

[0030]FIG. 1 also shows in section the spring element 2 made of elasticplastic. The spring element 2 is shaped in a rhombic configurationhaving radiused corners. FIG. 1 shows the corner points on the longdiagonal. The plane formed by the rhombic spring element 2 is referredto in the following as the spring element plane.

[0031] Also shown in FIG. 1 are two opposing locking elements 3connected in one integral piece with connecting bars 12. In thisarrangement the locking elements 3 are of a wedge-shaped configurationabutting with their abutment surface 34 against the horizontallyextending wall 37 of the detent elements 10 constructed as blind-endbores or depressions, after they were pushed by the radial bias exertedby the spring element 2 upward as far as the stop via cooperatingsliding and centering surfaces 40, 39. In this position, as in thedecoupled position, the locking elements 3 penetrate the passages 35 andengage in the undercut detent elements 10.

[0032] According to FIGS. 1 and 3 the connecting bars 12 are integrallyformed on the spring element 2 perpendicular to the spring elementplane. At their lower ends the connecting bars 12 have perpendicularlyextending guide grooves 5, as is particularly well visible in FIG. 3.

[0033] Furthermore, in FIGS. 1 and 3 provision is made at the fasteningpoint of the connecting bars 12 above the locking elements 3 fordiametrically opposed actuating devices 4 which are equally integrallyformed on the spring element 2 as a one-piece construction. In thisarrangement the actuating devices 4 are configured as bead-typepushbuttons which, according to FIG. 1, project out of the couplingsection of the drive part 7 through an opening 13. To prevent soiling ofthe drive part 7, provision is made for flexible rubber seals 14 whichcover the openings 13 and the actuating devices 4. The spring element 2is held in its position by guide ribs 8 and the annular collar 17 on thehousing 18 of the drive part 7. The guide grooves 5 shown in FIG. 3slide on the guide ribs 8 when the locking device is actuated.

[0034]FIG. 2 shows the same embodiment as FIG. 1, but the sectionextends in a 90-degree offset relation and some parts are omitted forthe sake of simplicity. Shown in FIG. 2 are the ejectors 9 arranged in a90-degree offset relation to the locking elements 3. The ejectors areconnected equally in a one-piece construction to the spring element 2 byway of connecting bars 11 (see FIG. 3) and are slightly wedge-shaped,forming on their bottom sides ramp surfaces 32 which engage abutmentsurfaces 33 of the tool shank 6 and which, when pressure is applied fromboth sides radially from without to within against the actuating devices4 (see the direction of the arrow X in FIG. 1) cause the ejectors 9 tomove radially outwardly precisely in the reverse direction, pushing thetool shank of FIG. 2 downward via the abutment surfaces 33, whichhowever is not shown in the drawings because only the assembled positionof the tool shank 6 and the drive part 2 is shown. As this occurs, thelocking elements 3 have already moved radially inwardly out of thedepressions 38 and released the tool shank 3 for axial movement. Attheir lower ends the connecting bars 11 also have guide grooves 5 whichare guided in radial direction by guide ribs 8 in that they embrace saidribs from above and the side. The ejectors 9 are shown in a perspectiveview in FIG. 3.

[0035] The spring element 2 shown in FIG. 3 as an individual part isinjection molded as an integral piece manufactured from an elasticthermoplastic material. The spring element 2 of an annular shape, andthe actuating devices 4 and the locking elements 3 fitted underneath toa connecting bar 12 are arranged at an angle of 90 degrees to theconnecting bars 11 on which the ejectors 9 and the downwardly open guidegrooves 5 are formed. The locking elements 3 are arranged on aconnecting bar 12 which has the guide grooves 5 further below.

[0036]FIG. 4 and FIG. 4a show a schematic functional view of thecoupling device of the invention, in which the spring element 2accommodated in the drive part 7 is shown as a broken line. In FIG. 4the tool shank 6 is shown in the locked state. In this state theactuating devices 4 are at their furthest apart. By contrast, theejectors 9 are arranged opposite each other at a shorter relativedistance. This becomes also apparent from the greatly simplified sketchin FIG. 4a, which shows a schematic plan view of a rhombic springelement 2.

[0037]FIGS. 5 and 5a show a second schematic functional view in whichthe actuating devices 4 of FIGS. 4 and 4a have been actuated in thedirection of the arrow A. As the result, the rhombic spring element 2deforms such that the locking elements 3 are unlocked and the ejectors 9separate the tool shank 6 from the drive part 7. This can be seenparticularly well in the schematic plan view of the rhombic springelement 2 in FIG. 5a. In the actuated position the ejectors 9 aresituated on the long diagonal of the rhombus, while the actuatingdevices 4 are to be found on the short diagonal. The locking devices 3fully disappear in the drive part, as becomes apparent from FIG. 5.

1. A coupling device (1) for an appliance for domestic use, inparticular a handheld blender or immersion blender, for connecting adrive part (7) to a tool shank (6), with a locking device (2) having atleast one locking element (3) being arranged on a coupling section (24)of the drive part (7), said locking element being in engagement with adetent element (10) of the tool shank (6) in the locked state,characterized in that said locking device (2) is constructed as anannular spring element and that in the area of the locking element (3)provision is made for an actuating device (4) causing, when actuated,the spring element (2) to be deformed elastically such that the lockingelement (3) becomes disengaged from the detent element (10).
 2. Thecoupling device (1) according to claim 1, characterized in thatdiametrically opposed on the spring element (2) is one locking element(3) each and that one detent element (10) each is provided at thecorresponding position on the tool shank (6).
 3. The coupling device (1)according to claim 1, characterized in that on the outer wall of thecoupling section (24) of the drive part (7) provision is made for atleast one opening (13) through which at least one actuating device (4)formed on the spring element (2) projects outwardly in the locked state.4. The coupling device (1) according to claim 3, characterized in thatdiametrically opposed on the spring element (2) is one actuating device(4) each which project out through the openings (13) provided on thedrive part (7).
 5. The coupling device (1) according to claim 4,characterized in that the actuating devices (4) are formed on the springelement (2) level with the locking elements (3).
 6. The coupling device(1) according to claim 1, characterized in that the locking device (2)is fabricated from a suitable thermoplastic material.
 7. The couplingdevice (1) according to claim 1, characterized in that the lockingdevice (2) includes at least one ejector (9) disposed in a 90 -degreeoffset relation to the locking element (3).
 8. The coupling device (1)according to claim 7, characterized in that diametrically opposed on thespring element (2) is one ejector (9) each and that the ejectors (9)include ramp surfaces (32) cooperating with corresponding abutmentsurfaces (33) on the tool shank (6).
 9. The coupling device (1)according to claim 1, characterized in that on the locking device (2)and in the coupling section of the drive part (7) provision is made forcorresponding guide devices (5, 8) guiding the spring element (2)radially towards the drive part (7).
 10. The coupling device (1)according to claim 7, characterized in that the locking device (2)includes a captivating device comprised of the ejector (9) formed on thespring element (2), said ejector in turn engaging within a passage (35)formed on the drive part (7).
 11. The coupling device (1) according toclaim 2, characterized in that the locking elements (3) are arranged onfirst connecting bars (12) integrally connected with the spring element(2).
 12. The coupling device (1) according to claim 2, characterized inthat the locking elements (3) are of a wedge-shaped configuration andthe detent elements (10) are in the form of depressions (38) whosehorizontally extending walls (37) abut against the abutment surfaces(34) and whose obliquely outwardly extending sliding surfaces (40) abutagainst centering surfaces (39) shaped to conform to the shape of thesliding surfaces (40).
 13. The coupling device (1) according to claim 7,characterized in that the ejectors (9) are arranged on second connectingbars (11) which are integrally formed with the spring element (2).